Early in 2018, Thomas Piketty, author of the bestselling 2013 book "Capital in the Twenty-First Century," wrote a detailed, fact-filled 160-page study that rejected everything that the Democratic Party establishment was telling us.

And it got completely ignored by the MSM, political pundits, and Democratic insiders.

Fortunately a writer at Slate noticed it.

The Republican Party has earned a reputation as the anti-science, anti-fact party — understandably, perhaps, given the GOP's policy of ignoring the evidence for global climate change and insisting on the efficacy of supply-side economics, despite all the research to the contrary. Yet ironically, it is now the Democratic Party that is wantonly ignoring mounds of social science data that suggests that promoting centrist candidates is a bad, losing strategy when it comes to winning elections. As the Democratic establishment and its pundit class starts to line up behind the centrist nominees for president — mainly, Joe Biden, Cory Booker and Kamala Harris — the party's head-in-the-sand attitude is especially troubling.
...First, the sheer amount of data analyzed in Piketty's paper is stunning. He and his researchers analyze voters in those three countries by income (broken into deciles), education, party, gender, religion and income disparity. The final 106 pages of the paper consist of graphs and charts. This is a seriously detailed data analysis that took years of work, and any intelligent political party operative should take it very seriously.

Much like his bestseller, Piketty absolutely buries you in data.
So what did he find? I'll quote directly from the study.

In the 1950s-1960s, the vote for “left-wing” (socialist-labour-democratic) parties was associated with lower education and lower income voters. This corresponds to what one might label a “class-based” party system: lower class voters from the different dimensions (lower education voters, lower income voters, etc.) tend to vote for the same party or coalition, while upper and middle class voters from the different dimensions tend to vote for the other party or coalition.
Since the 1970s-1980s, “left-wing” vote has gradually become associated with higher education voters, giving rise to what I propose to label a “multiple-elite” party system in the 2000s-2010s: high-education elites now vote for the “left”, while high-income/high-wealth elites still vote for the “right” (though less and less so).
I.e. the “left” has become the party of the intellectual elite (Brahmin left), while the “right” can be viewed as the party of the business elite (Merchant right).

If this sounds familiar, it's roughly what Thomas Frank has been saying for years (but without the hard data).
Neither party even pretends to represent the working class.

Two general lessons emerge from this research. First, with multi-dimensional inequality, multiple political equilibria and bifurcations can occur. Globalization and educational expansion have created new dimensions of inequality and conflict, leading to the weakening of previous class-based redistributive coalitions and the gradual development of new cleavages. Next, without a strong egalitarian-internationalist platform, it is difficult to unite low-education, low-income voters from all origins within the same coalition and to deliver a reduction in inequality.

I take that to mean a true progressive coalition requires strong universalistic policies (like Medicare For All). Incrementalism and Identity Politics will never unite the working class as a voting block, nor was it ever designed to.
Or to put it another way.

An "egalitarian-internationalist platform" means the kind of political platform that articulates a shared, global struggle among all of the poor and working-class people around the world — in other words, a class-conscience platform that recognizes that rich people are not on the same side as the rest of us, and have different interests and are eager to exploit us. And egalitarian means the opposite of nationalistic or xenophobic — united in a common class struggle, you might say, towards a mutual goal of universal civil rights.

In every election 40% of voters vote Republican and 40% vote Democrat.
The ruling elite compete for the remaining 20%, while ignoring the bigger picture:

Half of all eligible voters don't vote.

The reason is that nominating centrist Democrats who don't speak to class issues will result in a great swathe of voters simply not voting. Conversely, right-wing candidates who speak to class issues, but who do so by harnessing a false consciousness — e.g. blaming immigrants and minorities for capitalism's ills, rather than capitalists — will win back those same voters who would have voted for a more class-conscious left candidate. Piketty calls this a "bifurcated" voting situation, e.g. many voters will connect either with far-right xenophobic nationalists or left-egalitarian internationalists, but perhaps nothing inbetween.

Piketty's paper is an inconvenient truth for the Democratic Party. The party's leaders see themselves as the left wing of capital — supporting social policies that liberal rich people can get behind, never daring to enact economic reforms that might step on rich donors' toes. Hence, the establishment seems intent on anointing the centrist Democrats of capital, who push liberal social policies and neoliberal economic policies.

Which is why Democrats are hyper-sensitive to racism and sexism, because it doesn't cost them a dime, but have no problems at all with classism.
It's perfectly OK to rob people of their livelihoods and dignity, as long as you do it in a non-racist, non-sexist way.
These wealthy, highly educated people will not even see the destitute homeless person that they step over while going to an anti-Trump rally to voice their moral outrage about his tweets.